Antenna window and antenna pattern for electronic devices and methods of manufacturing the same

ABSTRACT

A housing for an electronic device, including an aluminum layer enclosing a volume that includes a radio-frequency (RF) antenna is provided. The housing includes a window aligned with the RF antenna; the window including a non-conductive material filling a cavity in the aluminum layer; and a thin aluminum oxide layer adjacent to the aluminum layer and to the non-conductive material; wherein the non-conductive material and the thin aluminum oxide layer form an RF-transparent path through the window. A housing for an electronic device including an integrated RF-antenna is also provided. A method of manufacturing a housing for an electronic device as described above is provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/973,939, filed Aug. 22, 2013, entitled ANTENNA WINDOW AND ANTENNAPATTERN FOR ELECTRONIC DEVICES AND METHODS OF MANUFACTURING THE SAME,which claims the benefit of U.S. Provisional Patent Application No.61/832,760, filed Jun. 7, 2013, entitled ANTENNA WINDOW AND ANTENNAPATTERN FOR ELECTRONIC DEVICES AND METHODS OF MANUFACTURING THE SAME,both of which are incorporated by reference herein in their entireties.

FIELD OF THE DESCRIBED EMBODIMENTS

The described embodiments relate generally to housings for electronicdevices adapted to include radio-frequency (RF) antennas. Moreparticularly, embodiments disclosed herein relate to metallic housingsfor portable electronic devices adapted to include radio-frequencyantennas.

BACKGROUND

Antenna architecture is an integral part of a consumer electronicsproduct. Housings and structural components are often made fromconductive metal, which can serve as a ground for an antenna. However,antennas require nonconductive regions or other isolation to provide agood radiation pattern and signal strength. To solve this problemconventional designs include a plastic antenna window or a plastic splitin a housing to separate the conductive metal. However, this approachbreaks the consistent visual profile of the device, deteriorating thecosmetic appeal of the metal surface. Also, replacing metallic portionsof the housing with softer materials weakens the underlying metal anduses device volume to fasten the parts together.

Therefore, what is desired is a housing for an electronic device thatintegrates antenna designs in a manner that is visually consistent withthe cosmetic appeal of the device and that provides structural supportfor the device and functional support for the antenna.

SUMMARY OF THE DESCRIBED EMBODIMENTS

In a first embodiment, a housing for an electronic device is provided.The housing may include an aluminum layer enclosing a volume thatincludes a radio-frequency (RF) antenna, the aluminum layer having awindow aligned with the RF antenna. The window includes a non-conductivematerial filling a gap in the aluminum layer and a thin aluminum oxidelayer adjacent to the aluminum layer and to the non-conductive material.The non-conductive material and the thin aluminum oxide layer form anRF-transparent path to allow transmission of substantially all RFradiation through the window.

In a second embodiment, a housing for an electronic device is provided.The housing may include an aluminum layer enclosing a number ofelectronic circuits. The housing also may also include an oxide layer onan exterior surface of the aluminum layer. The housing may additionallyinclude one or more radio-frequency (RF) antennas. The one or more RFantennas includes an electrically conductive path including a firstsegment and a second segment. The one or more RF antennas also includesa non-conductive material adjacent to the conductive path, thenon-conductive material electrically insulating the first segment of theelectrically conductive path from the second segment of the electricallyconductive path. The one or more RF antenna additionally includes anRF-transparent material layer adjacent to the hard material layer and tothe electrically conductive path. At least one of the first segment andthe second segment is part of the aluminum layer.

In a third embodiment, a method of manufacturing a housing for anelectronic device is provided. The method may include converting analuminum layer in the housing to an exterior aluminum oxide layer. Themethod may also include removing the aluminum layer adjacent to thealuminum oxide layer to form a gap in a window portion of the housing.The method may additionally include filling the gap in the windowportion with a non-conductive material. Accordingly, the gap allowstransmission of substantially all RF radiation through the windowportion.

In yet another embodiment, a method of forming a radio-frequency (RF)transparent window in an aluminum housing for an electronic device isprovided. The method may include inserting an RF transparent materialinto a window opening in the aluminum housing. The method may alsoinclude forming a thin aluminum layer on an exterior surface of thealuminum housing and the RF transparent material. The method may furtherinclude anodizing the thin aluminum layer to form an aluminum oxidelayer so that the aluminum oxide layer is adjacent to the RF transparentmaterial in the window opening, allowing transmission of substantiallyall RF radiation through the window.

Other aspects and advantages of the invention will become apparent fromthe following detailed description taken in conjunction with theaccompanying drawings which illustrate, by way of example, theprinciples of the described embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The described embodiments may be better understood by reference to thefollowing description and the accompanying drawings. Additionally,advantages of the described embodiments may be better understood byreference to the following description and accompanying drawings. Thesedrawings do not limit any changes in form and detail that may be made tothe described embodiments. Any such changes do not depart from thespirit and scope of the described embodiments.

FIGS. 1A-1C illustrate a portable electronic device, according to someembodiments.

FIGS. 2A-2C illustrate steps in a method of forming a housing for anelectronic device including a Radio-Frequency (RF) antenna, according tosome embodiments.

FIGS. 3A-3C illustrate steps in a method of forming a housing for anelectronic device including an RF antenna, according to someembodiments.

FIG. 4A illustrates a partial plan view of a housing for an electronicdevice including an RF antenna, according to some embodiments.

FIGS. 4B-4D illustrate steps in a method of forming a housing for anelectronic device including an RF antenna, according to someembodiments.

FIGS. 5A-5B illustrate steps in a method of forming a housing for anelectronic device including an RF antenna, according to someembodiments.

FIGS. 6A-6C illustrate a portable electronic device, according to someembodiments.

FIGS. 7A-7D illustrate steps in a method of forming a housing for anelectronic device including an RF antenna, according to someembodiments.

FIGS. 8A-8G illustrate steps in a method of forming a housing for anelectronic device including an RF antenna, according to someembodiments.

FIG. 9 illustrates a cross-sectional view of a housing for an electronicdevice including an RF antenna, according to some embodiments.

FIG. 10 illustrates a cross-sectional view of a housing for anelectronic device including an RF antenna, according to someembodiments.

FIG. 11A-11B illustrate steps in a method of forming a housing for anelectronic device including an RF antenna, according to someembodiments.

FIG. 12 illustrates a flow chart with steps in a method of forming ahousing for an electronic device including an RF antenna, according tosome embodiments.

FIG. 13 illustrates a flow chart with steps in a method of forming ahousing for an electronic device including an RF antenna, according tosome embodiments.

FIG. 14 illustrates a flow chart with steps in a method of forming ahousing for an electronic device including an RF antenna, according tosome embodiments.

In the figures, elements referred to with the same or similar referencenumerals include the same or similar structure, use, or procedure, asdescribed in the first instance of occurrence of the reference numeral.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

Representative applications of methods and apparatus according to thepresent application are described in this section. These examples arebeing provided solely to add context and aid in the understanding of thedescribed embodiments. It will thus be apparent to one skilled in theart that the described embodiments may be practiced without some or allof these specific details. In other instances, well known process stepshave not been described in detail in order to avoid unnecessarilyobscuring the described embodiments. Other applications are possible,such that the following examples should not be taken as limiting.

In the following detailed description, references are made to theaccompanying drawings, which form a part of the description and in whichare shown, by way of illustration, specific embodiments in accordancewith the described embodiments. Although these embodiments are describedin sufficient detail to enable one skilled in the art to practice thedescribed embodiments, it is understood that these examples are notlimiting; such that other embodiments may be used, and changes may bemade without departing from the spirit and scope of the describedembodiments.

The various aspects, embodiments, implementations or features of thedescribed embodiments can be used separately or in any combination.Various aspects of the described embodiments can be implemented bysoftware, hardware or a combination of hardware and software. Thedescribed embodiments can also be embodied as computer readable code ona computer readable medium for controlling manufacturing operations oras computer readable code on a computer readable medium for controllinga manufacturing line. The computer readable medium is any data storagedevice that can store data, which can thereafter be read by a computersystem. Examples of the computer readable medium include read-onlymemory, random-access memory, CD-ROMs, HDDs, DVDs, magnetic tape, andoptical data storage devices. The computer readable medium can also bedistributed over network-coupled computer systems so that the computerreadable code is stored and executed in a distributed fashion.

Electronic device housings consistent with the present disclosureinclude a hard, cosmetic anodized surface of aluminum. The anodizedsurface is nonconductive and thus is transparent to radio-frequency (RF)electronic radiation. In some embodiments, the anodized surface may havea thickness on the order of 10 microns (1 micron=1 μm=10⁻⁶ m). Byadjusting the anodization parameters the anodization depth can be madeto have a thickness of over 100 microns. A number of design techniques(outlined in the attachment) can be used to create a continuous,anodized, cosmetic aluminum surface that is selectively conductive incertain portions and non-conductive in other portions. This allows anantenna window or even an antenna to be patterned directly into thehousing. Such electronic device housing improves product cosmetics, andreduces the size of the device.

Antenna windows in aluminum enclosures are challenging. Prior solutionsinclude splits in housings and plastic covered antenna windows. Ourproposed solution is to use aluminum oxide as the antenna window.Aluminum oxide is non-conductive and transparent to RF. Aluminum oxideis created during the process of anodization. The thickness can benominally up to 100 um thick or higher by careful adjustment of theanodization parameters. The process, as outlined in the attached,includes anodization of the exterior housing and then etching away onthe interior of the housing antenna windows at desired locations forantenna windows, followed by filling in the etched portions withplastic, paint, or other suitable material to maintain structuralintegrity. The aluminum oxide can be substantially clear or transparent,allowing the filling material to show through. The resulting housing iscosmetically pleasing and without cracks or apparent plastic portions.

Accordingly, embodiments consistent with the present disclosure providea housing for an electronic device integrating antenna designs in amanner that is visually consistent with the cosmetic appeal of thedevice. In some embodiments, an electronic device housing providesstructural support for the device and functional support for the antennaintegrated in the device. In some embodiments, a housing for anelectronic device includes a window for an antenna, the window providingRF-transparency for the antenna signals while maintaining a consistentvisual appeal for the device. Also, the RF-transparent window maintainsa structural support for the housing.

FIG. 1A illustrates a plan view of a front face in a portable electronicdevice 10, according to some embodiments. Portable electronic device 10includes a housing 150 holding a display cover 20 and having a sensoraperture 30. Sensor aperture 30 may Portable electronic device 10 alsoincludes at least an RF antenna 50 which may be integrated into housing150. In some embodiments RF antenna 50 may be in the interior side ofhousing 150. In that regard, portable electronic device 10 may includemultiple RF antennas, some of which may be integrated into housing 150,and others may be included in the interior side of housing 150. While RFantenna 50 in FIG. 1A is shown as a coil wrapping around display cover20, other configurations are possible. Housing 150 may include anRF-transparent layer 100 over a hard material substrate 110. In someembodiments, RF-transparent layer 100 may be an oxide layer formed fromhard material substrate 110. For example, hard material layer 110 mayinclude an aluminum layer and RF-transparent layer 100 may be aluminumoxide formed from converting a portion of the aluminum layer.Accordingly, RF-transparent layer may be an exterior layer of housing150, and hard material layer 110 may be an interior layer of housing150.

FIG. 1B illustrates a cross-sectional view of portable electronic device10, according to some embodiments. The cross-section in FIG. 1B is takenalong segment A-A′ (cf. FIG. 1A). FIG. 1B illustrates a configurationwhere RF antenna 50 is integrated into housing 150. While RF antenna 50includes a conductive portion, the antenna is configured to includeportions of RF-transparent layer 120 separating different segments of RFantenna 50. As mentioned above, in some embodiments hard materialsubstrate 110 includes a metal. Thus, hard material layer 110 providesstructural support to the electronic device, and also a groundconnection for RF antenna 50, in some embodiments. RF-transparent layer100 may include an electrically resistive material (e.g., aluminumoxide) effectively isolating segments of RF antenna 50 from each otherand from other conductive portions of housing 150 (e.g., aluminum layer110). FIG. 1C illustrates a plan view of a back face in portableelectronic device 10, according to some embodiments. Accordingly, insome embodiments a cross section of housing 150 as shown in FIG. 1B mayinclude no conductive material, such as aluminum (e.g., layer 110) incertain portions of housing 150 (e.g., layers 120). Such embodimentsenable antenna 50 to be integrated within housing 150 as thenon-conductive material in layer 120 is adjacent to the conductive pathin antenna 50. The non-conductive material in layer 120 electricallyinsulates a first segment in antenna 50 from a second segment in theconductive path of antenna 50. FIG. 1C illustrates a sensor aperture 40which may be configured to allow a camera to receive visible light fromoutside of housing 150. In some embodiments aperture 40 may beconfigured to allow an audio device to transmit or receive acousticsignals to and from outside housing 150.

FIGS. 2A-2C illustrate steps in a method of forming housing 150 forelectronic device 10 including Radio-Frequency (RF) antenna 50,according to some embodiments. FIG. 2A illustrates a step of placing anon-conductive material 211 in a hard material layer 201 forming housing150. Hard material layer 201 may include an electrically conductivematerial such as a metal (e.g., aluminum). Non-conductive material 211may be a plastic, a ceramic material, or glass. In some embodiments,non-conductive material 211 may include a thermosetting polymer, anepoxy, or some other glue including a curable resin. The stepillustrated in FIG. 2A may include forming a gap in hard material layer201 and molding plastic material 211 inside the gap. Accordingly, thegap may have the profile of an antenna window, and be formed in aportion of housing 150 proximate or adjacent to RF antenna 50. FIG. 2Billustrates a step of coating a thin layer of hard material 205 on aside of housing 150 overlapping layers 201 and non-conductive material211. Layer 205 may include the same material as layer 201. For example,if layer 201 is aluminum, layer 205 may be formed by coating a thinaluminum layer on the side of housing 150, as illustrated in FIG. 2B.The step in FIG. 2B may include Physical Vapor Deposition (PVD) of ametal to form layer 205. Examples of PVD may include sputtering andother procedures known in the art. Accordingly, the step in FIG. 2B mayinclude metallization of a ceramics substrate by steps including ionvapor deposition, chemical vapor deposition (CVD), cathodic arcdeposition, plasma spray, and others known in the art. FIG. 2Cillustrates a step of oxidizing the thin layer of hard material 205 toform a thin RF-transparent layer 221. In some embodiments, thinRF-transparent layer 211 includes an aluminum oxide layer formed byanodization of thin aluminum layer 205. RF-transparent layer 211 caninclude metal, just not solid bulk metal or alloy that will block RFtransmission. As a result of the steps illustrates in FIGS. 2A-2C, aportion of housing 150 has a cross-section such that an RF-transparentpath is formed from an exterior side of housing 150 to an interior sideof housing 150.

FIGS. 3A-3C illustrate steps in a method of forming housing 150 forelectronic device 10 including antenna 50, according to someembodiments. FIG. 3A illustrates a step providing a layer of hardmaterial 201 (cf. FIGS. 2A-2C, above). FIG. 3B illustrates a step offorming RF-transparent layer 221 adjacent to layer 201 (cf. FIG. 2C).Accordingly, the step in FIG. 3B may include anodizing an aluminum layer201 to form aluminum oxide layer 221 with a pre-selected thickness. Insome embodiments, the thickness of aluminum oxide layer 221 may be about12 μm. Such an aluminum oxide layer may result from ‘consuming’ anapproximately 5 μm to 6 μm aluminum layer through anodization. FIG. 3Cillustrates a step of forming a non-conductive layer 231 in a portion ofhard material layer 201. The step in FIG. 3C may include a ‘hard’anodization process to form a thick aluminum oxide layer 231 having asimilar thickness as hard material layer 201. For example, inembodiments where hard material layer 201 includes aluminum, the step inFIG. 3C may include using Plasma Electrolytic Oxidation (PEO) to producea thick layer of alumina (aluminum oxide in crystalline form), alsoknown as sapphire, as non-conductive layer 231. In some embodiments, thestep in FIG. 3C may include use of a mask overlapping portions of hardmaterial layer 201 so that layer 231 separates portions of hard materiallayer 201, prior to anodizing layer 201. Accordingly, layer 231 may bethicker than layer 221. In some embodiments, layer 231 may be up to 50μm thick, or even more. Some embodiments consistent with the presentdisclosure may form a thinner aluminum oxide layer 221 on the exteriorportion of housing 150, and a thicker aluminum oxide layer 231 on theinterior portion of housing 150. Thus, a thinner aluminum oxide layer221 may be as layer 100 covering all or almost all of the exterior sideof housing 150, and a thicker aluminum oxide layer 231 may coverselected portions of the interior side of housing 150 (e.g., layer 120,cf. FIGS. 1A-1C).

FIG. 4A illustrates a partial plan view of a housing 450 for electronicdevice 10 including RF antenna 50, according to some embodiments.Housing 450 may include a honeycomb configuration where islands 451 madeof hard material 201 are isolated from one another by channels 421.Islands 451 may include a conductive material such as aluminum, andchannels 421 may include a non-conductive material (e.g., non-conductivematerial 211, cf. FIG. 2C). FIG. 4A illustrates a honeycomb structurehaving similar hexagonally shaped islands 451 adjacent to one another.The honeycomb structure can provide stiffness to RF antenna 50 and canprovide areas that are sufficiently thin so as to be fully anodized toRF transparent material. While this is an exemplary embodiment, one ofordinary skill would recognize that islands 451 may have any shape.Furthermore, islands 451 may have different shape and size from oneanother.

FIGS. 4B-D illustrate steps in a method of forming housing 450 forelectronic device 10 including RF antenna 50, according to someembodiments. FIG. 4B illustrates a step of forming micro perforations420 in a hard material layer 201 (cf. FIGS. 2A-2C and FIGS. 3A-3C).Micro perforations 420 can be used to reduce the thickness of hardmaterial layer 201 in areas of micro perforations 420 while maintainingits stiffness. In embodiments where hard material layer 201 includesaluminum, the micro perforations 420 goes through the aluminum andthrough an aluminum oxide layer adjacent to the aluminum. Microperforations 420 may be formed by laser machining of aluminum in hardmaterial layer 201. FIG. 4C illustrates a step of forming non-conductivelayer 231 from portions of hard material layer 201. Accordingly, thestep in FIG. 4C may include selectively anodizing the aluminum in hardmaterial layer 201 to form areas of aluminum oxide, which are RFtransparent. In some embodiments, anodizing forms an aluminum oxidelayer having a thickness of between about 5 to 300 microns. Inparticular, aluminum oxide can be formed at micro perforations 420 wherethe aluminum is very thin. Since the aluminum is thin at microperforations 420, these regions can have cross sections that are fullyanodized to aluminum oxide, thereby creating areas within RF antenna 50that are RF transparent. The step in FIG. 4C may include using a mask tocover a portion 461 of hard material 201. Portion 461 may form an islandof aluminum, a metal, or some other conducting material surrounded bynon-conductive layer 231. FIG. 4D illustrates a step of forming asupport layer 471 on a side of housing 150. Support layer 471 providesstructural integrity and stiffness to housing 150. In some embodiments,support layer 471 may include a fiberglass coating, or a thin layer ofglass or plastic. It is desirable that support layer 471 be made of anon-conducting material so as not to compromise the operation of an RFantenna integrated in housing 150. FIG. 4D also illustrates portions 421and 451 of housing 450 (cf. FIG. 4A).

FIGS. 5A-5B illustrate steps in a method of forming housing 450 forelectronic device 10 including RF antenna 50, according to someembodiments. FIG. 5A illustrates a step similar to the step illustratedin FIG. 4B. FIG. 5B illustrates a step of forming a non-conductive layer231 from portions of hard material layer 201, and forming anRF-transparent layer 221 on a side of housing 150, overlappingnon-conductive layer 231 and portion 461.

FIGS. 6A-6C illustrate a portable electronic device 10 including anantenna window 60, according to some embodiments. FIG. 6A illustrates aplan view of a front face in portable electronic device 10 includingantenna window 60, according to some embodiments. FIG. 6A includesdisplay cover 20 and sensor aperture 30, as described in detail above(cf. FIG. 1A). FIG. 6B illustrates a cross-sectional view of portableelectronic device 10 including antenna window 60, according to someembodiments. Antenna window 60 is placed in apportion of housing 150proximal to RF antenna 50. In some embodiments antenna window 60 may beadjacent to RF antenna 50. FIG. 6C illustrates a plan view of a backface in portable electronic device 10 including antenna window 60,according to some embodiments. FIG. 6C also includes sensor aperture 40,as described in detail above (cf. FIG. 1C). As mentioned above inreference to FIGS. 1A-1C, embodiments consistent with the presentdisclosure may include multiple RF antennas located in different areasin portable electronic device 10. For example, an RF antenna may beintegrated in housing 150 (cf. FIG. 1A), and another RF-antenna may bein the interior side of housing 150, adjacent to antenna window 60 (cf.FIG. 6B).

FIGS. 7A-7D illustrate steps in a method of forming housing 150 forelectronic device 10 including RF antenna 50, according to someembodiments. FIG. 7A illustrates a step of forming an RF-transparentlayer 221 adjacent to a hard material layer 201. The geometry of thecavity can be in the form of a pocket, trench, or any suitable shapethat does not break the plane of layer 221. FIG. 7B illustrates a stepof forming a cavity in hard material layer 201. The step in FIG. 7B mayinclude machining the cavity, or etching away a portion of material inlayer 201 to form the cavity. FIG. 7C illustrates a step of removing athin residual of material in layer 201 adjacent to layer 221 in thecavity. The cavity can be formed by laser ablation, chemical etch, orother suitable technique as recognized by a person of skill in the art.FIG. 7D illustrates a step of filling the cavity in layer 201 withnon-conductive material 211.

FIGS. 8A-8G illustrate steps in a method of forming housing 150 forelectronic device 10 including RF antenna 60, according to someembodiments. FIG. 8A illustrates a step similar to the step illustratedin FIG. 7A. FIG. 8B illustrates a step similar to step 7B illustrated inFIG. 7B. FIG. 8C illustrates a step of forming a masking layer 801around layers 201 and 221, including the cavity formed in the stepillustrated in FIG. 8B. FIG. 8D illustrates a step of selectivelyremoving masking layer 801 in an area overlapping a residual thicknessof material 201 adjacent to layer 221 in the cavity formed in the stepillustrated in FIG. 8B. The step illustrated in FIG. 8D may includeetching away masking layer 801 in the selected portion. FIG. 8Eillustrates a step of removing the hard material 201 left unmasked instep 8D. FIG. 8F illustrates a step of removing residual masking layer801. FIG. 8G illustrates a step of filling the cavity withnon-conductive material 211.

Accordingly, in embodiments of housing 150 for electronic device 10where the hard material layer 110 forming the housing is aluminum, someembodiments of an RF-antenna window may include removing all aluminummaterial in the window area (cf. FIGS. 7D and 8E). Such configurationenhances the RF-transparency of the window, as aluminum layers of even afew nm thick have a non-zero absorbance in the RF frequency spectrum.

FIG. 9 illustrates a cross-sectional view of housing 150 for electronicdevice 10 including RF antenna 50, according to some embodiments.Accordingly, FIG. 9 illustrates hard material layer 201, RF-transparentlayer 221, and non-conductive layer 211 in a gap of layer 201.Non-conductive layer 211 includes RF antenna 50. In some embodiments, RFantenna 50 includes a strip of conductive material (e.g., aluminum)adjacent to RF-transparent layer 221.

FIG. 10 illustrates a cross-sectional view of housing 150 for electronicdevice 10 including RF antenna 50, according to some embodiments.Accordingly, FIG. 10 illustrates hard material layer 201, RF-transparentlayer 221, and non-conductive layer 211 in a gap of layer 201.Non-conductive layer 211 includes RF antenna 50. In some embodiments, RFantenna 50 includes a strip of conductive material (e.g., aluminum)embedded within non-conductive layer 211.

FIG. 11A-11B illustrate steps in a method of forming housing 150 forelectronic device 10 including RF antenna 50, according to someembodiments. FIG. 11A illustrates a step of forming a gap in a hardmaterial layer 201. The step in FIG. 11A also includes placing a blockincluding RF-transparent layer 221 adjacent to non-conductive layer 211in the gap formed in layer 201. FIG. 11B illustrates a step of extendingRF-transparent layer 221 across the gap, overlapping hard material layer201.

FIG. 12 illustrates a flow chart with steps in a method 1200 of forminghousing 150 for electronic device 10 including RF antenna 50, accordingto some embodiments. Step 1210 includes forming a gap on the housing.The housing may include a hard material layer made of aluminum (e.g.,layer 110, cf. FIG. 1B). Accordingly, step 1210 may be as described indetail in relation to FIG. 2A. Step 1220 includes filling the gap with anon-conductive material. Accordingly, steps 1210 and 1220 may beincluded in the steps illustrated in detail in relation to FIG. 2A. Step1230 includes forming a thin material layer over the gap (cf. FIG. 2B).And step 1240 includes oxidizing the thin material layer (cf. FIG. 2C).Accordingly, step 1240 may include forming an RF-transparent layeradjacent to a portion of the hard material layer and the non-conductivematerial filling the gap in the hard material layer.

FIG. 13 illustrates a flow chart with steps in a method 1300 of forminghousing 150 for electronic device 10 including RF antenna 50, accordingto some embodiments. Step 1310 includes forming a first oxidized layeron a first side of a hard material layer. In some embodiments, step 1310may include anodizing an aluminum layer to form a thin RF-transparentlayer on one side (e.g., layer 221, cf. FIG. 3B). Step 1320 includesforming a second oxidized layer on a second side of the hard materiallayer (e.g., layer 231, cf. FIG. 3C).

FIG. 14 illustrates a flow chart with steps in a method 1400 of forminghousing 150 for electronic device 10 including RF antenna 50, accordingto some embodiments. Step 1410 includes forming an oxidized layer on ahard material layer. In some embodiments, step 1410 may includeanodizing an aluminum layer to form a thin RF-transparent layer (e.g.,layer 221, cf. FIGS. 7A and 8A). Step 1420 includes forming a gap on thehard material layer on a side opposite to the oxidized layer (cf. FIGS.7B and 8B). Step 1430 includes removing residual material from the hardmaterial layer adjacent to the oxidized layer in the gap (cf. FIGS. 7Cand 8C-F). Step 1440 includes filling the gap with a non-conductivematerial (cf. FIGS. 7D and 8G).

Embodiments of antenna windows and methods of manufacturing the same asdisclosed herein may also be implemented with other sensors included inelectronic device 10. For example, in some embodiments patch 60 mayinclude a touch sensitive pad configured to receive a touch from theuser. The touch sensitive pad may be capacitively coupled to anelectronic circuit configured to determine touch position and gestureinterpretation.

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the describedembodiments. However, it will be apparent to one skilled in the art thatthe specific details are not required in order to practice the describedembodiments. Thus, the foregoing descriptions of specific embodimentsare presented for purposes of illustration and description. They are notintended to be exhaustive or to limit the described embodiments to theprecise forms disclosed. It will be apparent to one of ordinary skill inthe art that many modifications and variations are possible in view ofthe above teachings.

What is claimed is:
 1. A housing for an electronic device, comprising: ametal layer; a first and a second gap formed through a thickness of themetal layer and arranged to form an electrically isolated segment of themetal layer, wherein the electrically isolated segment forms a radiofrequency (RF) antenna; a non-conductive material filling the first andthe second gaps in the metal layer; and a metal oxide layer formed on anexterior surface of the metal layer and extending across the first andthe second gaps and the electrically isolated segment, wherein the metaloxide layer forms an RF-transparent window.
 2. The electronic device ofclaim 1, wherein the non-conductive material is a metal oxide.
 3. Theelectronic device of claim 1, wherein the metal layer is aluminum. 4.The electronic device of claim 1, wherein the non-conductive materialcomprises a polymer.
 5. The electronic device of claim 1, furthercomprising a third gap formed through the thickness of the metal layer.6. The electronic device of claim 1, wherein the metal layer comprisesaluminum and the metal oxide layer comprises aluminum oxide.
 7. A methodof manufacturing a housing for an electronic device, the methodcomprising: forming a metal layer; forming a first and a second gapthrough a thickness of the metal layer to isolate a segment of the metallayer; filling the first and second gaps with a non-conductive material;and forming a metal oxide layer on the metal layer, wherein the metaloxide layer extends across the first and the second gaps and thesegment.
 8. The method of claim 7, wherein the non-conductive materialis a metal oxide.
 9. The method of claim 7, wherein the metal oxidelayer is formed before the first and second gaps.
 10. The method ofclaim 7, wherein forming the first and the second gaps is performed byconverting portions of the metal layer to a metal oxide.
 11. The methodof claim 10, wherein forming the first and the second gaps includesmasking a portion of an interior surface of the metal layer andperforming a Plasma Electrolytic Oxidation (PEO) at an unmasked portionof an interior surface of the metal layer.
 12. The method of claim 7,wherein the filling includes using a material selected from the groupconsisting of a plastic, a thermosetting polymer, and a resin.
 13. Themethod of claim 7, forming the first and the second gaps includesmachining the metal layer, etching away the metal layer, or both. 14.The method of claim 7, wherein forming the first and the second gapsincludes forming micro-perforations in an interior side of the metallayer to establish thin wall sections that allow substantially all ofthe metal layer at the thin wall sections to be anodized.
 15. The methodof claim 7, further comprising: forming a third gap in the metal layer.16. The method of claim 15, wherein one or more RF antennas are formedin the metal layer.
 17. The method of claim 7, wherein the metal oxidelayer is formed by first depositing an aluminum layer on a surface ofthe housing by performing a process selected from the group consistingof physical vapor deposition, chemical vapor deposition, ion vapordeposition, cathodic arc deposition, and plasma spray deposition.